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Article Modifications of Knuth Randomness Tests for Integer and Binary Sequences(2018) Koçak, Onur; Sulak, Fatih; Doğanaksoy, Ali; Uğuz, MuhiddinGenerating random numbers and random sequences that are in-distinguishable from truly random sequences is an important task for cryptog-raphy. To measure the randomness, statistical randomness tests are applied tothe generated numbers and sequences. Knuth test suite is the one of the .rststatistical randomness suites. This suite, however, is mostly for real numbersequences and the parameters of the tests are not given explicitly.In this work, we review the tests in Knuth Test Suite. We give test para-meters in order for the tests to be applicable to integer and binary sequencesand make suggestions on the choice of these parameters. We clarify how theprobabilities used in the tests are calculated according to the parameters andprovide formulas to calculate the probabilities. Also, some tests, like Per-mutation Test and Max-of-t-test, are modi.ed so that the test can be usedto test integer sequences. Finally, we apply the suite on some widely usedcryptographic random number sources and present the results.Article Bağıntı ve Fonksiyonlar Konusunda Yapılan Yaygın Hataların Belirlenmesi ve Giderilmesi Üzerine Boylamsal Bir Çalışma(2007) Sonay, Zeynep Polat; Şahiner, YeterBu çalışma boylamsal bir çalışmadır. Araştırmanın birinci basamağı, 2004–2005 öğretim yı-lında Hacettepe Üniversitesi Sınıf Öğretmenliği Bölümü’nde birinci sınıfta okumakta olan 190 öğrenci üzerinde uygulanmıştır. Bu aşamada, öğrencilerin bağıntı ve fonksiyonlar konusunda yaptıkları yaygın hatalar belirlenmiş, sınıflandırılmış ve bu hataların temelinde yatan nedenler araştırılmıştır. Araştırmanın ikinci basamağı, 2005–2006 öğretim yılında aynı üniversitenin aynı bölümünde ve yine birinci sınıfta okumakta olan 97 öğrenci ile yürütülmüştür. Bu aşamada, “Sınıf öğretmenliği öğrencilerinin fonksiyonlar konusunda yaptıkları yaygın hatalar giderilebilir mi?” sorusuna yanıt aranmaktadır. Çalışmanın sonuçları, birinci aşamada saptanan yaygın hatalar dikkate alınarak hazırlanmış olan ders içeriği, dersin işleniş planı ve kullanılan metot ile hataların büyük ölçüde giderildiğini göstermiştir.Article A Second Pre-Image Attack and A Collision Attack To Cryptographic Hash Function Lux(2017) Sulak, Fatih; Koçak, Onur; Saygı, Elif; Öğünç, Merve Ö.; Bozdemır, BeyzaCryptography is a science that provides the security of informationin communication. One of the most important sub-branches of cryptographyis the hash functions. Hash functions are known as the digital ...ngerprints.Following the recent attacks on the widely used hash functions MD5 and SHA1 and the increase in computational power, the need for a new hash functionstandard has arisen. For this purpose, US National Institute of Standards andTechnology (NIST) had announced a competition to select a standard hashfunction algorithm which would eventually become the Third Secure HashAlgorithm, SHA-3. Initially 64 algorithms were submitted to NIST and 51 ofthem were announced as the First Round Candidates. After an analysis period,14 of these algorithms were announced as the Second Round Candidates, and5 algorithms were announced as Finalists. The winner of the competition,Keccak, was announced in 2012.LUX is one of the 64 algorithms submitted to the SHA-3 competition byNikolic et al.function. For LUX-256, Schmidt-Nielsen gave a distinguisher and later Wu etal. presented collision attacks, both of which for reduced rounds of LUX. As aresult of these attacks, LUX is eliminated in the ...rst round. In this work, we...rst give a procedure for the second preimage attack. Then we extend this tothe collision and second preimage attacks for the reduced rounds of LUX hashfamily. Moreover, we implement the attacks and give the speci...c examples bytaking the padding into consideration.
